Manufacture of sodium citrate



Kntented 22, ltlZh QFHQEQ WELTEBGLAESER, 0F EROORLYN, NEW YQBK,

MBLQ'UFAGTUBEDF SQIDIUM CITRATE.

To all whom 2'29 may concern:

Be it known that I. WALTER GLAnsnn, a citizen of the United States, and a resident .of-Brooklyn,.county of Kings and State of v New York, have invented s new and useful Improvement in' the Manufacture of Sodium Citrate, of which the following is a specitication; the principle of the invention being herein explained and the best mode in which i heve contemplated applying that principie, so as to distinguish it from other inventions.

The present invention, relating, as indiceted, to the manufecture of sodium citrate, is directed to an improved method involving e single operation and the use of relatively inexpensive reagents. To the accomplishment of the foregoing and related ends, said invent-ion, then, consists oi the means hereinafter fully described and particularly pointed out in the claims.

"lhe following description sets "forth in detail one approved method of carrying out the invention, such disclosed mode, however, constituting but one of the various ways in which the principle of the invention may be used.

Sodium citrate is ordinarily made by dissolving in citrig acid, which requires of course that citric acid be made first, and the manufacture of this compound is expensive. The present invention is based upon my discovery that calcium citrate is completely decomposed when treated in the cold by an aqueous solution of an elkali metal salt, such so sodium carbonate. It is essential that the treatment be carried on at a low tem erature, which should be below 30 1, it is desirable that there be prescut 21 small amount of ammonia as this us sists the double decompcsition for the reason thet calcium citrate is soluble in ammonia.

The reactions which teire place when celciuln citrate is thus created in the cold with sodium carbonate ere indicutod in the fol- 9, 1920. Serial H0, 357,292.

lowing equations, and produce sodium citrate and calcium carbonate.

It is not necessary to use sodium carbonate,

as other alkali metal salts, such as sodium sulphate or'sodium bisulphate or phosphate .may be used to effect the same decomposition of calcium citrate.

Calciumcitratc occurs in nature in small quantities, but is usually manufactured by neutralizing: thejuice of lemons, limes and similar fruits with milk of'lime. It should first be powdered fine, and when treated in aqueous solution with the alkali metal salt, the solution should be agitated, and, as already stated, the solution must be kept below a temperature of 30 C. After the reaction ms gone to completion and thecalcium can bonete has been precipitated and removed the liquor may be evaporated to obtain solid sodium cit-rate.

Other modes of applying the principle of my invention may be employed instead of the one explainedchange being made as regards the method herein disclosed, provided the step or steps stated by any of the following claims or the equivalent of such stated step or stepsbe employed.

1 therefore particularly point out and distinctly-claim as my invention.

l. The 'incthod of. making alkali metal citrate by dissolving calcium citrate indilute smmonin and precipitating an insoluble calcium salt therefrom by the corresponding alkali metal salt, at a temperature below.

2. The method of making sodium citrate by dissolving calcium citrate in dilute emmonie and precipitedtinu an insoluble celcium salt therefrom by the corresponding sodium salt at e temperature below 30 C. Signed by me, this 17th day of Junuery,

WALTER GLAESER. 

